1. Field of the Invention
The present invention relates to a projection display apparatus and, more particularly, to a projection display apparatus including a light amount adjustment mechanism.
2. Description of the Background Art
In recent years, a projection display apparatus has been developed as one type of image display apparatus, and put to practical use. With conventional projection display apparatuses, light leaks and stray light (unwanted light) have occurred in a variety of optical elements constituting optical systems such as induction optical systems, projection lenses and the like. In particular, when images are projected onto a screen in a dark room, a dark image does not sufficiently appear dark. This has presented a problem such that insufficient contrast results in the lack of a sense of realism. In particular, a projection display apparatus using a liquid crystal light valve is not capable of completely cutting off transmitted light because the liquid crystal light valve has the characteristic of cutting off the transmitted light in accordance with the polarization property of the light, and has limitations in meeting the requirement by video signal processing. Thus, there is a strong demand for improving the contrast in the projection display apparatus using the liquid crystal light valve.
To solve the problem as mentioned above, a projection display apparatus as disclosed in, for example, International Publication No. WO 2005/026835 (Page 51, FIG. 6) has been devised. This projection display apparatus includes, for example, a light shielding plate disposed between a first lens array and a second lens array for the purpose of improving the contrast of images projected onto a screen and the like, and causes the light shielding plate of a planar configuration to pivot in response to a video signal, thereby controlling the amount of light directed to a light valve in accordance with the video signal.
In the projection display apparatus including a conventional light amount adjustment mechanism as mentioned above, however, some light reaches lens cells of the second lens array other than lens cells thereof which are in contact with an optical axis C when the maximum amount of light exiting from the first lens array is cut off. Thus, there has been a problem such that the conventional projection display apparatus finds difficulties in providing high contrast.